Microlens and an image sensor including a microlens

ABSTRACT

A microlens, an image sensor including the microlens, a method of forming the microlens and a method of manufacturing the image sensor are provided. The microlens includes a polysilicon pattern, having a cylindrical shape, formed on a substrate, and a round-type shell portion enclosing the polysilicon pattern. The microlens may further include a filler material filling an interior of the shell portion, or a second shell portion covering the first shell portion. The method of forming a microlens includes forming a silicon pattern on a semiconductor substrate having a lower structure, forming a capping film on the semiconductor substrate over the silicon pattern, annealing the silicon pattern and the capping film altering the silicon pattern to a polysilicon pattern having a cylindrical shape and the capping film to a shell portion for a round-type microlens, and filling an interior of the shell portion with a lens material through an opening between the semiconductor substrate and an edge of the shell portion. The image sensor includes a microlens formed by a similar method and a photodiode having a cylindrical shape.

PRIORITY STATEMENT

This U.S. non-provisional application claims the benefit of priorityunder 35 U.S.C. §119 from Korean Patent Application No. 10-2006-0070296,filed on Jul. 26, 2006, in the Korean Intellectual Property Office(KIPO), the disclosure of which is incorporated herein in its entiretyby reference.

BACKGROUND

1. Field

Example embodiments relate to an image sensor including a microlens, animage sensor including the microlens, a method of forming the microlensand a method of manufacturing the image sensor. Other exampleembodiments relate to a method of forming a microlens which increases anoptical efficiency, a microlens capable of increasing opticalefficiency, an image sensor including the microlens and a method ofmanufacturing the image sensor.

2. Description of the Related Art

Microlenses are used in a variety of fields (e.g., image sensors, liquidcrystal display (LCD) devices and optical communications systems).Microlenses can be used as an objective lens to record or reproduceinformation with respect to an optical disk drive (ODD) (e.g., a compactdisk (CD) or digital versatile disk (DVD)).

An image sensor including a microlens is a semiconductor device used toconvert an optical image to an electric signal. The conventional imagesensor with the microlens may include a charge coupled device (CCD) anda complimentary metal oxide semiconductor (CMOS) image sensor.

The CCD has a plurality of MOS capacitors arranged in proximity to eachother. The CCD operates by storing electric charges (carriers) generatedby light in the MOS capacitors or by the movement of electric chargesbetween the MOS capacitors. The CMOS image sensor utilizes CMOStechnology wherein a control circuit and a signal processing circuitfunction as a peripheral circuit. The CMOS image sensor includes aplurality of unit pixels and a CMOS circuit that controls the outputsignals of the unit pixels.

FIG. 1 is a diagram illustrating a partial cross-sectional view of aconventional CMOS image sensor.

Referring to FIG. 1, the conventional CMOS image sensor includes anisolation layer (not shown) defining an active area on a semiconductorsubstrate SUB and a photodiode PD between the device isolation layers.The photodiode PD receives incident light and stores electric charges.

A first interlayer dielectric film ILD₁ is formed on the surface of thesemiconductor substrate SUB where the device isolation layer and thephotodiode PD are formed. Although not illustrated, the first interlayerdielectric film ILD₁ may be formed in a multi-layer structure. A metalwiring M, forming a unit pixel, is provided (or formed) in the firstinterlayer dielectric film ILD₁. The metal wiring M is provided (orformed) such that it does not block the light incident on the photodiodePD. The metal wiring M may be formed in a multi-layer structure.

A color filter layer CF, having sections dyed in red, green and/or blue,is formed on the first interlayer dielectric film ILD₁ over thephotodiode PD. A second interlayer dielectric film ILD₂ is formed on thecolor filter layer CF and a portion of the first interlayer dielectricfilm ILD₁. The second interlayer dielectric film ILD₂ functions as anovercoat layer to overcome step and/or adjust the focal length of amicrolens.

A round-type microlens ML is formed on the second interlayer dielectricfilm ILD₂ over the photodiode PD. The microlens ML functions byconcentrating the incident light on the photodiode PD.

Although not illustrated, a protection film may be further provided onthe first interlayer dielectric film ILD₁ to protect the photodiode PDand metal wiring M from the degradation due to the intrusion of externalmoisture. A planarization layer may be provided on the protection layerto overcome step and/or increase adhesiveness.

In the conventional image sensor, the optical efficiency is degradedbecause a dead zone (an area where light cannot be concentrated) existsbetween the microlenses. The dead zone is generated during the formationof the microlens as described below.

FIGS. 2A through 2C are diagrams illustrating cross-sectional views of amethod of forming a conventional microlens.

Referring to FIG. 2A, an interlayer dielectric film ILD, which functionsas an overcoat layer, is formed on a semiconductor substrate (not shown)having a desired lower structure (not shown). A photoresist layer PR iscoated over the interlayer dielectric film ILD.

Referring to FIG. 2B, a desired area of the photoresist layer PR (e.g.,an area other than an area for forming a microlens) is exposed. The areais developed with a developer to form a photoresist pattern PRP.

Referring to FIG. 2C, the photoresist pattern PRP is allowed to reflowat a temperature greater than a glass transition temperature Tg (e.g.,120° C.-200° C.) to form a round-type microlens ML.

As described above, the microlens ML may be formed in a reflow processusing photoresist. Due to the limits in resolution of exposureequipment, it is difficult to decrease the area between the photoresistpattern PRP less than a predetermined value. As the area betweenneighboring microlens ML increases, a dead zone forms.

In the conventional image sensor, the light concentration of themicrolens ML is degraded if the incident light is inclined. If theincident light is input inclined, then a portion of the incident lightpassing through the microlens ML may not reach the photodiode PDcorresponding thereto, causing the image sensor to malfunction.

SUMMARY

Example embodiments relate to a microlens, an image sensor including themicrolens, a method of forming the microlens and a method ofmanufacturing the image sensor. Other example embodiments relate to amethod of forming a microlens which increases optical efficiency, amicrolens capable of increasing optical efficiency, an image sensorincluding the microlens and a method of manufacturing the image sensor.

Example embodiments provide a method of forming a microlens whichdecreases the optical efficiency degradation caused by the formation ofa dead zone in an image sensor and simultaneously increases the lightconcentration. Example embodiments provide a microlens including apolysilicon pattern formed on a semiconductor substrate, a round-typeshell portion for the microlens, wherein the round-type shell portionencloses the polysilicon pattern, and a filler material filling aninterior of the shell portion. The polysilicon pattern may have acylindrical shape.

According to other example embodiments, a microlens including apolysilicon pattern formed on a semiconductor substrate, a round-typefirst shell portion for the microlens, wherein the round-type firstshell portion encloses the polysilicon pattern, and a second shellportion covering the first shell portion is provided. The polysiliconpattern may have a cylindrical shape.

According example embodiments, a method of forming a microlens includesforming a silicon pattern on a semiconductor substrate having a lowerstructure, forming a capping film on the semiconductor substrate over(or covering) the silicon pattern, annealing the silicon pattern and thecapping film to change (or alter) the silicon pattern to a polysiliconpattern having a cylindrical shape and the capping film to a shellportion for a round-type microlens, and filling the interior of theshell portion with a lens material through an opening between thesemiconductor substrate and an edge of the shell portion generated (orformed) during the change (or altering) of the capping film to the shellportion.

According to other example embodiments, a method of forming a microlensincludes forming a silicon pattern on a semiconductor substrate having alower structure, forming a capping film on the semiconductor substrateover (or covering) the silicon pattern, annealing the silicon patternand the capping film to change (or alter) the silicon pattern to apolysilicon pattern having a cylindrical shape and the capping film to afirst shell portion for a round-type microlens, and forming a secondshell portion for the microlens over (or covering) the first shellportion.

According to other example embodiments, a method of forming a microlensincludes forming an interlayer dielectric film having a contact hole ona semiconductor substrate, forming a silicon plug in the contact hole,forming a silicon pattern on the contact hole and the interlayerdielectric film around (or covering) the contact hole, forming a cappingfilm on the interlayer dielectric film over (or covering) the siliconpattern, annealing the silicon pattern, the silicon plug, and thecapping film to change (or alter) the silicon pattern to a polysiliconpattern having a cylindrical shape and the capping film to a shellportion for a round-type microlens, and filling the interior of theshell portion with a lens material through an opening between thesemiconductor substrate and an edge of the shell portion generated (orformed) during the change (or altering) of the capping film to the shellportion.

According to yet other example embodiments, a method of forming amicrolens includes forming an interlayer dielectric film having acontact hole on a semiconductor substrate, forming a silicon plug in thecontact hole, forming a silicon pattern on the contact hole and theinterlayer dielectric film around (or covering) the contact hole,forming a capping film on the interlayer dielectric film over (orcovering) the silicon pattern, annealing the silicon pattern, thesilicon plug, and the capping film to change (or alter) the siliconpattern to a polysilicon pattern having a pole (or cylindrical) shapeand the capping film to a first shell portion for a round-typemicrolens, and forming a second shell portion for the microlens on theinterlayer dielectric film to cover (or around) the first shell portion.

The silicon pattern and the silicon plug may be formed of amorphoussilicon or polysilicon. The silicon pattern may have a width of 10Å-50000 Å. The silicon pattern may have a thickness of 10 Å-50000 Å.

The capping film may be formed of silicon oxide or zirconium oxide.

Annealing may include excimer laser annealing. Annealing may beperformed at an intensity of 100 mJ/cm²-3000 mJ/cm².

The polysilicon pattern having the pole (or cylindrical) shape may havea width less than a width of the silicon pattern. The polysiliconpattern may have a height greater than a height of the silicon pattern.

The lens material filling (or formed in) the interior of the shellportion may be a silicon oxide film or a photoresist film.

The second shell portion may be formed of silicon oxide or zirconiumoxide.

According to example embodiments, an image sensor includes asemiconductor substrate, a first portion of a photodiode formed bydoping impurities in a surface of the semiconductor substrate, aninterlayer dielectric film formed on the semiconductor substrate andhaving a contact hole partially exposing the first portion of thephotodiode, a second portion of the photodiode formed of dopedpolysilicon on the contact hole and having a height greater than aheight of the interlayer dielectric film, a round-type first microlensformed on the interlayer dielectric film over (or covering) the secondportion of the photodiode, and a color filter layer formed on the firstmicrolens.

The microlens may include a shell portion and an interior portion. Theinterior portion may be filled with a lens material. In other exampleembodiments, the interior portion may be empty.

The first microlens may include a round-type shell portion formed on anupper surface of the second portion of the photodiode. The firstmicrolens may have an edge separated from the interlayer dielectric filmand a filler material filling the interior portion. The round-type shellportion may be formed of silicon oxide or zirconium oxide. The fillermaterial may be formed of silicon oxide or photoresist.

The microlens may include a round-type first shell portion formed on anupper surface of the second portion of photodiode. The microlens mayhave an edge separated from the interlayer dielectric film. Themicrolens may have a second shell portion formed on the first shellportion and the interlayer dielectric film around the first shellportion. The first shell portion may be formed of silicon oxide orzirconium oxide. The second shell portion may be formed of silicon oxideor zirconium oxide.

A color filter layer may be formed on a surface of the first microlens.The color filter layer may not contact the first microlens. Anotherinterlayer dielectric film may be interposed between the color filterlayer and the first microlens.

The image sensor may include a second microlens formed on the colorfilter layer with a dielectric film interposed therebetween. The imagesensor may include a dielectric film formed on the interlayer dielectricfilm to cover (or over) the color filter layer, a polysilicon patternhaving a cylindrical shape formed on the dielectric film over the secondportion of the photodiode, and a round-type second microlens formed onthe dielectric film over (or covering) the polysilicon pattern.

The second microlens may include a shell portion and an interiorportion. The interior portion may be filled with a lens material or maybe empty. The structure and material thereof are the same as theabove-described microlens.

According to example embodiments, a method of manufacturing an imagesensor includes forming a first portion of a photodiode by dopingimpurities in a surface of a semiconductor substrate, forming a firstinterlayer dielectric film having a contact hole partially exposing thefirst portion of the photodiode on the semiconductor substrate, forminga silicon plug in the contact hole and a first silicon pattern (having afirst height and a width greater than a diameter of the contact hole) onthe contact hole and the first interlayer dielectric film, forming afirst capping film on the first interlayer dielectric film to cover (orover) the first silicon pattern, annealing the first silicon pattern,the silicon plug, and the first capping film to change (or alter) thefirst silicon pattern and the silicon plug to a first polysiliconpattern and the first capping film to a shell portion for a round-typefirst microlens wherein the first polysilicon pattern has a secondheight greater than the first height and functions as a second portionof the photodiode, and filling the interior of the shell portion with alens material through an opening between the first interlayer dielectricfilm and an edge of the shell portion formed during the change of thecapping film to the shell portion, and forming a color filter layer onthe shell portion.

According to example embodiments, a method of manufacturing an imagesensor includes forming a first portion of a photodiode by dopingimpurities in the surface of a semiconductor substrate, forming a firstinterlayer dielectric film having a contact hole partially exposing thefirst portion of the photodiode on the semiconductor substrate, forminga silicon plug in the contact hole and a first silicon pattern (having afirst height and a width greater than the diameter of the contact hole)on the contact hole and the first interlayer dielectric film, forming afirst capping film on the first interlayer dielectric film over thesilicon pattern, annealing the first silicon pattern, the silicon plugand the first capping film to form a first polysilicon pattern from thefirst silicon pattern and the silicon plug and the first capping film toa first shell portion for a round-type first microlens wherein the firstpolysilicon pattern has a second height greater than the first heightand functions as a second portion of the photodiode, forming a secondshell portion for the first microlens on the first shell portion and theinterlayer film, and forming a color filter layer on the second shellportion.

The silicon plug may be formed of amorphous silicon or polysilicon. Thesilicon pattern may be formed of amorphous silicon or polysilicon. Thesilicon pattern has a width of 10 Å-50000 Å. The silicon pattern has athickness of 10 Å-50000 Å.

The capping film may be formed of silicon oxide or zirconium oxide. Thelens material filling (or positioned in) the interior of the shellportion for the second microlens may be a silicon oxide film or aphotoresist film. The second shell portion may be formed of siliconoxide or zirconium oxide.

Annealing may include excimer laser annealing performed at an intensityof 100 mJ/cm²-3000 mJ/cm².

After forming the color filter layer, a dielectric film may be formed onthe interlayer dielectric film over (or covering) the color filterlayer. A second silicon pattern may be formed on the dielectric filmover the first silicon pattern. A second capping film may be formed onthe second silicon pattern. The second silicon pattern and the secondcapping film may be annealed to change (or alter) the second siliconpattern to a second polysilicon pattern having a cylindrical shape andthe second capping film to a first shell portion for a round-type secondmicrolens. A second shell portion for the second microlens may be formedon the first shell portion for the second microlens and the dielectricfilm around the first shell portion.

The second silicon pattern may be formed of amorphous silicon orpolysilicon. The second silicon pattern may be formed having a width of10 Å-50000 Å. The second silicon pattern may have a thickness of 10Å-50000 Å.

The second capping film may be formed of silicon oxide or zirconiumoxide. The second polysilicon pattern having the shape of a cylindricalmay have a smaller width and a greater height than the second siliconpattern. The second shell portion for the second microlens may be asilicon oxide film or a zirconium oxide film.

Annealing may include excimer laser annealing performed at an intensityof 100 mJ/cm²-3000 mJ/cm².

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings. FIGS. 1-18 represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is a diagram illustrating a partial cross-sectional view of aconventional CMOS image sensor;

FIGS. 2A through 2C are diagrams illustrating cross-sectional views of amethod for forming a conventional microlens;

FIGS. 5A through 5D are diagrams illustrating cross-sectional views of amethod of forming a microlens according to an example embodiments;

FIG. 6 is a diagram illustrating a cross-sectional view of a method offorming a microlens according to example embodiments;

FIGS. 7A through 7C are diagrams illustrating cross-sectional views of amethod of forming a microlens according to example embodiments;

FIG. 8 is a diagram illustrating a cross-sectional view of a method offorming a microlens according to example embodiments;

FIG. 9 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments;

FIG. 10 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments;

FIG. 11 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments;

FIGS. 12A through 12G are diagrams illustrating cross-sectional views ofa method of manufacturing an image sensor according to exampleembodiments;

FIG. 13 is a diagram illustrating a plan view image of an amorphoussilicon pattern before excimer laser annealing (ELA) is performed;

FIG. 14 is a diagram illustrating a plan view image of a polysiliconpattern formed by ELA—the amorphous silicon pattern of FIG. 13 at anintensity of 950 mJ/cm²;

FIG. 15 is a diagram illustrating a cross-sectional view of thepolysilicon pattern and a shell portion for a microlens formed accordingto an example embodiment;

FIGS. 16A and 16B are diagrams illustrating cross-sectional views of amethod of manufacturing an image sensor according to exampleembodiments;

FIGS. 17A and 17D are diagrams illustrating cross-sectional views of amethod of manufacturing an image sensor according to exampleembodiments; and

FIG. 18 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare shown. In the drawings, the thicknesses of layers and regions may beexaggerated for clarity.

Detailed illustrative embodiments are disclosed herein. However,specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Thisinvention may, however, may be embodied in many alternate forms andshould not be construed as limited to only the example embodiments setforth herein.

Accordingly, while the example embodiments are capable of variousmodifications and alternative forms, embodiments thereof are shown byway of example in the drawings and will herein be described in detail.It should be understood, however, that there is no intent to limitexample embodiments to the particular forms disclosed, but on thecontrary, the example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope of the invention.Like numbers refer to like elements throughout the description of thefigures.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the example embodiments. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the scope of the example embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or a relationship between a feature and anotherelement or feature as illustrated in the figures. It will be understoodthat the spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the Figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, for example, the term “below” can encompass both anorientation which is above as well as below. The device may be otherwiseoriented (rotated 90 degrees or viewed or referenced at otherorientations) and the spatially relative descriptors used herein shouldbe interpreted accordingly.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures). As such, variationsfrom the shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, may be expected. Thus,example embodiments should not be construed as limited to the particularshapes of regions illustrated herein but may include deviations inshapes that result, for example, from manufacturing. For example, animplanted region illustrated as a rectangle may have rounded or curvedfeatures and/or a gradient (e.g., of implant concentration) at its edgesrather than an abrupt change from an implanted region to a non-implantedregion. Likewise, a buried region formed by implantation may result insome implantation in the region between the buried region and thesurface through which the implantation may take place. Thus, the regionsillustrated in the figures are schematic in nature and their shapes donot necessarily illustrate the actual shape of a region of a device anddo not limit the scope.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

In order to more specifically describe example embodiments, variousaspects will be described in detail with reference to the attacheddrawings. However, the present invention is not limited to the exampleembodiments described.

Example embodiments relate to an image sensor including a microlens, animage sensor including the microlens, a method of forming the microlensand a method of manufacturing the image sensor. Other exampleembodiments relate to a method of forming a microlens which increases anoptical efficiency, an image sensor including the microlens and a methodof manufacturing the image sensor.

FIGS. 5A through 5D are diagrams illustrating cross-sectional views of amethod of forming a microlens according to example embodiments.

Referring to FIG. 5A, an interlayer dielectric film ILD is formed on asemiconductor substrate SUB and a silicon pattern SP is formed on theinterlayer dielectric film ILD. The silicon pattern SP may be formed ofamorphous silicon or polysilicon having a width of 10 Å-50,000 Å and/ora thickness of 10 Å-50,000 Å.

A capping film C is formed on the interlayer dielectric film ILD over(or covering) the silicon pattern SP. The capping film C may be asilicon oxide film or zirconium oxide film which exhibits highertransmissivity. The capping film C may be conformably formed on asurface of the silicon pattern SP and the interlayer dielectric filmILD. The silicon pattern SP and the capping film C are annealed.Annealing may include excimer laser annealing (hereinafter referred toas “ELA”) performed by an excimer laser. The intensity of the ELA may be100 mJ/cm²-3000 mJ/cm².

If the excimer laser is emitted, then the laser penetrates (or proceeds)a lower layer through the capping film C. The lower layer istransparent. As such, the laser concentrates on the silicon pattern SPrather than the interlayer dielectric film ILD of a silicon oxide film.The temperature of the silicon pattern SP rapidly increases. The siliconpattern SP is partially, or completely, melted. The degree of meltingmay be controlled by the intensity of the excimer laser.

Referring to FIG. 5B, the silicon pattern SP melted by the excimer lasermay have a semispherical shape caused by surface tension. As the meltedsilicon pattern gradually cools down, seeds for crystallization aregenerated (or formed) in the lower center portion thereof. The seeds areformed in the lower center portion of the melted silicon because theflow of fluid in the lower center portion is smaller than other portionsof the melted silicon. The poly-crystallization proceeds (or grows) inthe upward direction from the seeds located in the lower center portion.Reference mark SP′ indicates a silicon pattern during the process ofpoly-crystallization.

During poly-crystallization, the capping film C has a certain degree offlexibility such that the shape thereof may be round (e.g., a roundroof). As the edge portions (or ends) of the capping film C having around roof are separated from the interlayer dielectric film ILD, anopening portion is formed (or generated). Reference mark C′ indicatesthe capping film C during the change (or re-shaping) process.

Referring to FIG. 5C, a polysilicon pattern P having a shape of a pole(or cylindrical shape) is formed from the silicon pattern SP through thepoly-crystallization by ELA. A shell portion S is formed for around-type microlens from the capping film C. The polysilicon pattern Pand the shell portion S may be formed simultaneously. A width of thepolysilicon pattern P is less than a width of the silicon pattern SP anda height of the polysilicon pattern P is greater than a height of thesilicon pattern SP. Although not illustrated, part of the capping film Cmay remain on the interlayer dielectric film ILD.

Referring to FIG. 5D, a lens material F fills the interior of the shellportion S (e.g., an area under the shell portion S) through an openingportion between the interlayer dielectric film ILD and the shell portionS. A round-type microlens ML_(a) is formed from the shell portion S andthe lens material F filling the interior of the shell portion S.

The lens material F filling the interior of the shell portion S may be asilicon oxide film or a photoresist film. If the silicon oxide film isformed by LPCVD (low pressure chemical vapor deposition), then theinterior of the shell portion S may be filled with the silicon oxidefilm through the opening. If the photoresist film is used, then theinterior of the shell portion S may be filled by the flux of thephotoresist film. For example, if the photoresist film is used, then aphotoresist film being flux is coated (or formed) with a height greaterthan the shell portion S, filling the interior of the shell portion S.If the photoresist film outside the shell portion S is removed using theshell portion S as an etching mask, then the photoresist film remainsinside the shell portion S.

FIG. 6 is a diagram illustrating a cross-sectional view of a method offorming a microlens according to example embodiments. Exampleembodiments of the method are similar to in the steps shown withreference to FIG. 5A-5C. Thus, for the sake of brevity, the stepssubsequent to FIG. 5C will be described below. For the convenience ofexplanation, the shell portion S of FIG. 5C is referred to as a firstshell portion S₁ in FIG. 6.

Referring to FIG. 6, a second shell portion S₂ for a microlens is formedon the interlayer dielectric film ILD over the first shell portion S₁.The second shell portion S₂ may be formed of silicon oxide or zirconiumoxide. A microlens ML_(b) is formed having the first and second shellportions S₁ and S₂. The microlens ML_(b) is formed having an emptyinterior.

FIGS. 7A through 7C are diagrams illustrating cross-sectional views of amethod of forming a microlens according to example embodiments. Adescription of elements in FIGS. 7A-7C that are similar to elements inFIGS. 5A-5D will be omitted for the sake of brevity.

Referring to FIG. 7A, after an interlayer dielectric film ILD is formedon a semiconductor substrate SUB, a desired portion of the interlayerdielectric film ILD is etched to form a contact hole H. The contact holeH partially exposes the semiconductor substrate SUB. A silicon plug SHis formed in the contact hole H. A silicon pattern SP is formed on thecontact hole H. The interlayer dielectric film ILD is formed around thecontact hole H. The silicon plug SH may be formed of amorphous siliconor poly silicon. A capping film C is formed on the interlayer dielectricfilm ILD over the silicon pattern SP.

The silicon pattern SP, the silicon plug SH and the capping film C maybe annealed using an excimer laser having an intensity of 100mJ/cm²-3000 mJ/cm². If the excimer laser is emitted, then the laserproceeds (or penetrates) into a lower layer through the capping layer C.The temperature of the silicon pattern SP and the silicon plug SH mayincrease rapidly such that the silicon pattern SP and the silicon plugSH are partially, or completely, melted.

Referring to FIG. 7B, the silicon pattern SP melted by the excimer lasermay have a semispherical shape caused by surface tension. As the meltedsilicon plug SH and silicon pattern SP gradually cool down, seeds forpoly-crystallization are generated (or formed) in the boundary portionsthereof or the lower portion of the silicon plug SH.Poly-crystallization proceeds (or grows) upward from the seeds. As themelted silicon pattern SP is cooled, the silicon pattern SP is formedwith a pole, or cylindrical, shape.

During multi-crystallization, the capping film C has a certain degree offlexibility such that the shape thereof may be round (e.g., a roundroof). As the edge portions (or ends) of the capping film C having around roof are separated from the interlayer dielectric film ILD, anopening portion is formed. A polysilicon pattern P having a cylindricalshape is formed from the silicon plug SH and the silicon pattern SP bythe ELA. The shell portion S for a round-type microlens is formed fromthe capping film C. Referring to FIG. 7C, a lens material F fills theinterior of the shell portion S (e.g., an area under the shell portionS) through an opening portion between the interlayer dielectric film ILDand the shell portion S. A round-type microlens ML_(a) is formed havingthe shell portion S and the lens material F filling the interior of theshell portion S.

FIG. 8 is a diagram illustrating a cross-sectional view of a method offorming a microlens according to example embodiments. A description ofelements in FIG. 8 that are similar to elements in FIGS. 7A-7C will beomitted for the sake of brevity. For the convenience of explanation, theshell portion S of FIG. 7B is referred to as a first shell portion S₁ inFIG. 8.

Referring to FIG. 8, a second shell portion S₂ for a microlens is formedon the interlayer dielectric film ILD over the first shell portion S₁.The second shell portion S₂ may be formed of the same material as thesecond shell portion S₂ described with reference to FIG. 6. Themicrolens ML_(b) is formed having the first and second shell portions S₁and S₂. The microlens ML_(b) may have an empty interior.

Because the microlens (as described below) is formed by swelling thecapping film C using ELA opposed to the conventional photolithographyand reflow processes, the dead zone (which is the interval between themicrolenses) may be reduced. The dead zone may be more easily reducedwhen the microlens is formed by adding the second shell portion S₂outside the first shell portion S₁.

Example embodiments provide an image sensor including a microlens formedaccording to the methods described above. In the image sensor accordingto example embodiments, the polysilicon pattern P described withreference to FIGS. 7A through 7C and FIG. 8 may be used as part of aphotodiode.

FIG. 9 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments. FIG. 10 is a diagramillustrating a partial cross-sectional view of an image sensor accordingto example embodiments.

Referring to FIGS. 9 and 10, an image sensor may include a first portionPD₁ of a photodiode PD formed by doping impurities in the surface of thesemiconductor substrate SUB. The first portion PD₁ may be a structure inwhich a first impurity region and a second impurity region aresequentially formed (or deposited). In other example embodiments, thefirst portion PD₁ may be formed by depositing (or forming) a singleimpurity region.

The interlayer dielectric film ILD having the contact hole H thatpartially exposes the first portion PD₁ (e.g., a center portion) isformed on the semiconductor substrate SUB. The interlayer dielectricfilm ILD may be in a multi-layer structure. A metal wiring M, whichforms a unit pixel, may be provided in the interlayer dielectric filmILD. The metal wiring M may be positioned such that it does not blockincident light. The metal wiring M may be formed in a multi-layerstructure.

A second portion PD₂ of the photodiode PD is formed in the contact holeH. The second portion PD₂ may be formed of doped polysilicon having aheight greater than a height of the interlayer dielectric film ILD. Thesecond portion PD₂ of the photodiode may be formed of an impurityregion.

In other example embodiments, the second portion PD₂ may be in astructure in which the first impurity region and the second impurityregion are sequentially formed (or deposited). The second portion PD₂and the first portion PD₁ function as a photodiode.

In FIGS. 9 and 10, respectively, the round-type microlenses ML_(a) andML_(b) are formed on the interlayer dielectric film ILD over the secondportion PD₂. A color filter layer CF is formed on a surface of themicrolenses ML_(a) and ML_(b). The microlenses ML_(a) and ML_(b) may bedivided into a shell portion and/or an interior portion (e.g., an areaunder the shell portion). The interior may be filled with a lensmaterial as described in reference to FIGS. 5 and 7. In other exampleembodiments, the interior may be empty as described with reference toFIG. 6.

A first-type microlens, as shown in FIG. 9, may be formed of theround-type shell portion S and a filler material F. The round-type shellportion S may be formed on an upper surface of the second portion PD₂ ofthe photodiode. The round-type shell portion S may be separated from theinterlayer dielectric film ILD. The edge (or end) of the round-typeshell portion S may be separated form the interlayer dielectric filmILD. The filler material F that fills the interior of the shell portionS. The shell portion S of the first-type microlens ML_(a) may be formedof silicon oxide or zirconium oxide. The filing F may be formed ofsilicon oxide or photoresist.

A second-type microlens, as shown in FIG. 10, may include the round-typefirst shell portion S₁ and the second shell portion S₂. The round-typefirst shell portion S₁ is formed on the upper surface of the secondportion PD₂ of the photodiode. The round-type first shell portion S₁ isseparated from the interlayer dielectric film ILD. The second shellportion S₂ is formed on the first shell portion S₁ and contacts theinterlayer dielectric film ILD. The first and second shell portions S₁and S₂ of the second-type microlens ML_(b) may be formed of siliconoxide or zirconium oxide.

Because the first-type and second-type microlens are formed according tothe method described above opposed to the conventional photolithographyand reflow processes, the dead zone between the microlenses may bereduced. Because the second-type is a structure in which the secondshell portion S₂ is formed outside of the first shell portion S₁, thedead zone may be more easily reduced.

Because the photodiode PD includes the first portion PD₁ in thesemiconductor substrate SUB and the second portion PD₂ having a pole (orcylindrical) shape near the center of the photodiode PD₁, theconcentration of the photodiode PD increases. If the incident light isinclined, then malfunction of the image sensor due to the loss of lightmay be prevented because the second portion PD₂ decreases loss of light.

The image sensor according to example embodiments may further include asecond microlens formed on the color filter layer CF with a dielectricfilm interposed therebetween. The color filter layer CF may be formed onthe microclines ML_(a) or ML_(b) with another interlayer dielectric filminterposed between the color filter layer CF and the microlens ML_(a) orML_(b).

FIG. 11 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments. For the convenience ofexplanation, the microlens ML_(a) of FIG. 9 is referred to as a firstmicrolens ML_(a-1) in FIG. 11, the interlayer dielectric film ILD ofFIG. 9 is referred to as a first interlayer dielectric film ILD₁ in FIG.11, and the metal wiring M of FIG. 9 is referred to as a first metalwiring M₁ in FIG. 11.

Referring to FIG. 11, a color filter layer CF is formed on the firstmicrolens ML_(a-1) with the second interlayer dielectric film ILD₂interposed therebetween. A third interlayer dielectric film ILD₃ isformed on the color filter layer CF. A second metal wiring M₂ having asimilar shape as the first metal wiring M₁ may be provided in the thirdinterlayer dielectric film ILD₃.

A polysilicon pattern P₂ having a pole (or cylindrical) shape is formedon the third interlayer dielectric film ILD₃ over an area where thesecond portion PD₂ is formed. The second microlens ML_(b-2) is formed onthe interlayer dielectric film ILD₃ over the polysilicon pattern P.

As shown in FIG. 11, the second microlens ML_(b-2) is formed on an uppersurface of the polysilicon pattern P₂ and enclosing the same. The secondmicrolens ML_(b-2) may include a first shell portion S₂₋₁ and a secondshell portion S₂₋₂. The first shell portion S₂₋₁ for a round-type secondmicrolens is separated from the third interlayer dielectric ILD₃. Inother example embodiments, an edge (or end) of the first shell portionS₂₋₁ may be separated from the third interlayer dielectric ILD₃. Thesecond shell portion S₂₋₂ for the second microlens may be formed on thesecond shell portion S₂₋₁ and the interlayer dielectric film ILD₃.

Although the microlens ML_(b-2) is shown in FIG. 11 is empty (in otherwords, the second-type microlens), the microlens ML_(b-2) may be formedhaving the same structure and of the same material as the microlensML_(a) described with reference to FIG. 9 or the microlens ML_(b)described with reference to FIG. 10.

If the image sensor has a dual microlens, as shown in FIG. 11, then thewidth of the upper microlens is greater than the width of the lowermicrolens. Also, the lower microlens may be a first-type microlens andthe upper microlens may be formed a second-type microlens.

Hereinafter, a method of manufacturing an image sensor according toexample embodiments will be described.

FIGS. 12A through 12G are diagrams illustrating cross-sectional views ofa method of manufacturing an image sensor according to exampleembodiments.

Referring to FIG. 12A, a first portion PD₁ of a photodiode PD is formedby doping impurities in a surface of a semiconductor substrate SUB. Aninterlayer dielectric film ILD having a contact hole H partiallyexposing the first portion PD₁ of the photodiode PD is formed on thesemiconductor substrate SUB. The interlayer dielectric film ILD may bein a multi-layer structure. A metal wiring M forming a unit pixel may beprovided in the interlayer dielectric film ILD. The metal wiring M maybe in a multi-layer structure.

Referring to FIG. 12B, if a silicon plug SH is formed in the contacthole H, then a silicon pattern SP is formed on the contact hole H andthe interlayer dielectric film ILD. The silicon pattern SP may have afirst height and a width greater than the contact hole H. The siliconplug SH and silicon pattern SP may be formed simultaneously orsequentially. The silicon plug SH and silicon pattern SP may be formedof amorphous silicon or polysilicon. The silicon pattern SP may beformed in a variety of shapes (e.g., a circle, rectangle, etc.). Thesilicon pattern SP may have a width of 10 Å-50000 Å and/or a thicknessof 10 Å-50000 Å. The silicon plug SH and silicon pattern SP may be dopedwith impurities. If impurities are not doped in the silicon pattern SPduring the formation of the silicon pattern SP, then the silicon patternSP is doped with impurities in the subsequent step in order for thesilicon pattern SP to function as photodiode.

Referring to FIG. 12C, the capping film C is formed on the interlayerdielectric film ILD over the silicon pattern SP. The capping film C maybe a film exhibiting a higher transmissivity (e.g., a silicon oxide filmor a zirconium film). The capping film C may be formed to a uniformthickness. The silicon pattern SP, silicon plug SH and capping film Care annealed (e.g., excimer laser annealing (ELA)). The annealing may beperformed at an intensity of 100 mJ/cm²-3000 mJ/cm².

As described above, if the excimer laser is emitted, then the laserproceeds (or penetrates) into the lower layer through the capping layerC. The laser is concentrated on a portion of the silicon pattern SP andthe silicon plug SH rather than the interlayer dielectric film ILD of asilicon oxide film. The temperature of the silicon pattern SP and thesilicon plug SH increases rapidly such that the silicon pattern SP andthe silicon plug SH are partially, or completely, melted. The degree ofmelting may be controlled according to the intensity of the excimerlaser.

Referring to FIG. 12D, the silicon pattern SP melted by the excimerlaser tends to have a semispherical shape caused by surface tension. Asthe melted silicon pattern SP and silicon plug SH gradually cool down,seeds for poly-crystallization are generated (or formed) in the lowercenter portion thereof. The seeds are generated (or formed) in the lowercenter of the melted silicon because the flow of fluid in the lowercenter of the melted silicon is smaller than other areas of the meltedsilicon. Poly-crystallization proceeds (or grows) in the upwarddirection from the seeds in the lower center. Reference mark SP′indicates the silicon pattern and silicon plug duringpoly-crystallization.

During poly-crystallization, a capping film C formed on the siliconpattern SP has a certain degree of flexibility such that the shapethereof is round (e.g., a round roof). The capping film C having a roundroof may not contact the interlayer dielectric film ILD. The edge (orend) of the capping film C may not contact the interlayer dielectricfilm ILD. Reference mark C′ indicates the capping film duringpoly-crystallization.

Referring to FIG. 12E, the polysilicon pattern having the cylindricalshape is formed from the silicon plug SH and silicon pattern SP duringpoly-crystallization by ELA. A shell portion S for the round-typemicrolens is simultaneously formed from the capping film. Thepolysilicon pattern has a height greater than a height of the siliconpattern SP. The polysilicon pattern may be the second portion PD₂ ofphotodiode PD. If the silicon pattern SP is an undoped material, thenthe doping process may be performed in the polysilicon pattern afterpoly-crystallization.

Referring to FIG. 12F, a lens material F is filled in an interior of theshell portion S (e.g., an area under the shell portion S) through anopening between the interlayer dielectric film ILD and the shell portionS. The lens material F may be formed of silicon oxide film orphotoresist film.

As described above, if the silicon oxide film is formed by LPCVD, thenthe interior of the shell portion S may be filled through the opening.If the photoresist film is used, then the interior of the shell portionS may be filled by the flux of the photoresist film. A microlens ML_(a)is formed that includes the shell portion S and the lens material Ffilling the interior of the shell portion S.

Referring to FIG. 12G, a color filter layer CF is formed on a surface ofthe microlens ML_(a).

FIG. 13 is a diagram illustrating a plan view image of an amorphoussilicon pattern (a-Si) before excimer laser annealing (ELA) isperformed. FIG. 14 is a diagram illustrating a plan view image of apolysilicon pattern (a-Si) formed by ELA the amorphous silicon patternof FIG. 13 at an intensity of 950 mJ/cm². FIG. 15 is a diagramillustrating a cross-sectional view of the shell portion S for around-type microlens and the polysilicon pattern (poly-Si) having acylindrical shape formed according to example embodiments.

FIGS. 16A and 16B are diagrams illustrating cross-sectional views amethod of manufacturing an image sensor according to exampleembodiments. A description of elements in FIGS. 16A and 16B that aresimilar to elements in FIGS. 12A-12G will be omitted for the sake orbrevity. For the convenience of explanation, the shell portion S of FIG.12E is referred to as the first shell portion S₁ in FIGS. 16A and 16B.

Referring to FIG. 16A, a second shell portion S₂ for a microlens ML_(b)is formed on the first shell portion S₁ and the interlayer dielectricfilm ILD. The second shell portion S₂ may be formed of silicon oxide orzirconium oxide. The microlens ML_(b) is formed having the first andsecond shell portions S₁ and S₂.

Referring to FIG. 16B, a color filter layer CF is formed on a surface ofthe second shell portion S₂.

FIGS. 17A and 17D are diagrams illustrating cross-sectional views of amethod of manufacturing an image sensor according to exampleembodiments. A description of elements in FIGS. 17A-17D that are similarto elements in FIGS. 12A-12G will be omitted for the sake or brevity.For the convenience of explanation, the microlens ML_(a) of FIG. 12F isreferred to as the first microlens ML_(a-1) in FIGS. 17A through 17D,the shell portion S of FIG. 12F is referred to as the first shellportion S₁ in FIGS. 17A through 17D, the interlayer dielectric film ILDof FIG. 12F is referred to as the first interlayer dielectric film ILD₁in FIGS. 17A through 17D and the metal wiring M of FIG. 12F is referredto as the first metal wiring M₁ in FIGS. 17A through 17D.

Referring to FIG. 17A, a second interlayer dielectric film ILD₂ isformed on the first interlayer dielectric film ILD, over the microlensML_(a-1). A surface of the second interlayer dielectric film ILD₂ isplanarized. The color filter layer CF is formed on a portion of thesecond interlayer dielectric film ILD₂ over the microlens ML_(a-1). Athird interlayer dielectric film ILD₃ is formed over the color filterlayer CF. A second metal wiring M₂ may be formed in the third interlayerdielectric film ILD₃. The second metal wiring M₂ is arranged such thatthe wiring does not block the incident light, contrary to the firstmetal wiring M₁. The third interlayer dielectric film ILD₃ and secondmetal wiring M₂ may be in a multi-layer structure.

Referring to FIG. 17B, a second silicon pattern SP₂ on formed in aportion of the third interlayer dielectric film ILD₃. The second siliconpattern SP₂ is formed over the silicon pattern SP. A second capping filmC₂ is formed on the third interlayer dielectric film ILD₃ over thesecond silicon pattern SP₂. The material, width and/or thickness of thesecond silicon pattern SP₂ and second capping film C₂ may be the same asthe silicon pattern SP and/or capping film C. By emitting an excimerlaser to the semiconductor substrate SUB residual, poly-crystallizationof the second silicon pattern SP₂ may be performed using the same methodas described above. The shape of the second capping film C₂ is altered(or changed).

Referring to FIG. 17C, a second polysilicon pattern P₂ having acylindrical shape is formed from the second silicon pattern SP₂ throughpoly-crystallization by ELA. In example embodiments, a first shellportion S₂₋₁ of the round-type second microlens is formed from thesecond capping film C₂ simultaneously with the formation of the secondpolysilicon pattern SP₂.

Referring to FIG. 17D, a second shell portion S₂₋₂ for the secondmicrolens is formed on the first shell portion S₂₋₁ for the secondmicrolens and the interlayer dielectric film ILD₃. A second microlensML_(b-2) of the second-type is formed having two shell portions and anempty interior.

Although the second microlens described with reference to FIGS. 17A-17Dis a second-type microlens, in other example embodiments the secondmicrolens may be a first-type microlens, in which the interior of thesecond microlens is filled. The image sensor having a dual microlens maybe manufactured by the same method as the example embodimentsdescribed-above. In other example embodiments, the first microlens inthe lower portion may be of the second-type while the second microlensin the upper portion may be a first-type or a second-type microlens.

According to example embodiments, the image sensor having a newstructure is manufactured based on the principle that if a transparentcapping film is formed over a silicon pattern, which is subsequentlypoly-crystallized by ELA, then the silicon pattern becomes a polysiliconpattern having a cylindrical shape and the capping film becomes a shellportion for a round-type microlens.

Because the fundamental structure of the microlens is formed by swellingthe capping film opposed to using the conventional photolithography andreflow processes, the dead zone (which is the interval between themicrolenses) may be reduced. The dead zone may also decrease if themicrolens is formed by adding the second shell portion to the firstshell portion formed from the capping film.

According to other example embodiments, if the incident light isinclined, then the light loss is prevented by the photodiode because thesecond portion PD₂ of photodiode (which has a pole, or cylindrical,shape) is formed under the center portion of the microlens.

As such, example embodiments may increase the optical efficiency of theimage sensor and/or prevent (or decrease the likelihood of) malfunctionof the sensor due to the light loss. Example embodiments may alsoincrease the efficiency of a lens because the material used for the lensmaterial (e.g., a silicon oxide film) has a higher refractive index thanthe conventional photoresist film. Because the ELA process thatconcentrates a laser on the amorphous silicon pattern is used, a highertemperature process is not needed, reducing costs associated with highertemperature processes and/or property deterioration.

FIG. 18 is a diagram illustrating a partial cross-sectional view of animage sensor according to example embodiments.

Referring to FIG. 18, the image sensor includes a photodiode PD dopedwith impurities in a surface of a semiconductor substrate SUB. A firstinterlayer dielectric film ILD₁ is formed on the semiconductor substrateSUB including the photodiode PD. Metal wiring M may be provided in thefirst interlayer dielectric film ILD₁. A color filter layer CF is formedover the interlayer dielectric film ILD where the photodiode PD isformed. A second interlayer dielectric film ILD₂ is formed on the firstinterlayer dielectric film ILD, over the color filter layer CF. Apolysilicon pattern P having a cylindrical shape is formed on a desiredportion of the second interlayer dielectric film ILD₂. The polysiliconpattern P may be formed over a central portion of the second interlayerdielectric film ILD₂. The polysilicon pattern P may be formed over thephotodiode PD. The polysilicon pattern P may be formed by the samemethod as the method for forming the polysilicon pattern P of FIG. 17C.A first shell portion S₁ for a round-type microlens having an edgeseparated from the second interlayer dielectric film ILD₂ is formed onan upper surface of the polysilicon pattern P. A second shell portion S₂is formed on the first shell portion S₁ and the second interlayerdielectric film ILD₂. The first and second shell portions S₁ and S₂ formthe microlens ML_(b) of the second-type. The first and second shellportions S₁ and S₂ may be formed by the same method as the method forforming the first and second shell portions S₂₋₁ and S₂₋₂ according tothe example embodiments described with reference to FIGS. 17A through17D.

According to example embodiments, the dead zone may be decreased despitenot having a perpendicular photodiode portion. If the width of thepolysilicon pattern P is formed smaller than the width of the microlens,then the light blocked by the polysilicon pattern P may negligiblebecause the width of the polysilicon pattern P may be controlled by theintensity of the excimer laser.

Because the capping film is formed over the silicon patternpoly-crystallized by ELA, the polysilicon pattern (having thecylindrical shape) for the photodiode is formed from the silicon patternand simultaneously the shell portion for the round-type microlens isformed from the capping film.

Because the fundamental structure of the microlens is formed by swellingthe capping film by ELA opposed to using the conventionalphotolithography and reflow processes, the dead zone may be reduced. Thedead zone may be further reduced if the microlens is formed by addingthe second shell portion to the first shell portion formed from thecapping film.

According to other example embodiments, if the incident light isinclined, then the loss of light may be reduced because theperpendicular photodiode is provided in the lower center portion of themicrolens.

In other example embodiments, because the efficiency of a lensincreases, a material (e.g., a silicon oxide film) having a higherrefractive index than the conventional photoresist film is used as alens material.

Because the ELA process that concentrates a laser on the amorphoussilicon pattern is used, a higher temperature process may not benecessary, decreasing the costs associated with higher temperatureprocesses and/or property deterioration.

Although not illustrated, any well-known processes may be used insubsequent steps that are necessary to complete the manufacture of theimage sensors according to example embodiments.

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in example embodiments withoutmaterially departing from the novel teachings and advantages of thepresent invention. For example, the structure of the image sensoraccording to example embodiments and a manufacturing method thereof canbe used not only for a CMOS image sensor but also for a variety of imagesensors. In some cases, the interlayer dielectric film may function asan overcoat layer to overcome step and/or adjust the focal length of amicrolens. The constituent elements can be diverse as an overcoat layer,a protection layer, or a planarization layer is added. Accordingly, allsuch modifications are intended to be included within the scope of thisinvention as defined in the claims. In the claims, means-plus-functionclauses are intended to cover the structures described herein asperforming the recited function, and not only structural equivalents butalso equivalent structures. Therefore, it is to be understood that theforegoing is illustrative of the present invention and is not to beconstrued as limited to the specific embodiments disclosed, and thatmodifications to the disclosed embodiments, as well as otherembodiments, are intended to be included within the scope of theappended claims. The present invention is defined by the followingclaims, with equivalents of the claims to be included therein.

1. An image sensor, comprising: a first portion of a photodiode formedby doping impurities in a surface of a semiconductor substrate; aninterlayer dielectric film formed on the semiconductor substrate, theinterlayer dielectric film having a contact hole partially exposing thefirst portion of the photodiode; a second portion of the photodiodeformed of doped polysilicon on the contact hole, the second portionhaving a height greater than a height of the interlayer dielectric film;a round-type first microlens formed on the interlayer dielectric filmover the second portion of the photodiode; and a color filter layerformed on the first microlens.
 2. The image sensor of claim 1, whereinthe first microlens includes a shell portion and an interior portion,wherein the interior portion is empty or filled with a lens material. 3.The sensor of claim 1, wherein the first microlens includes a round-typeshell portion enclosing the second portion of the photodiode, theround-type shell portion having an edge separated from the interlayerdielectric film; and a filler material filling the interior of the shellportion.
 4. The image sensor of claim 3, wherein the round-type shellportion is formed of silicon oxide or zirconium oxide.
 5. The imagesensor of claim 3, wherein the filler material is formed of siliconoxide or photoresist.
 6. The image sensor of claim 1, wherein the firstmicrolens includes: a round-type first shell portion formed enclosingthe second portion of the photodiode, the round-type first shell havingan edge separated from the interlayer dielectric film; and a secondshell portion formed on the first shell portion and the interlayerdielectric film.
 7. The image sensor of claim 6, wherein the first shellportion is formed of silicon oxide or zirconium oxide.
 8. The imagesensor of claim 6, wherein the second shell portion is formed of siliconoxide or zirconium oxide.
 9. The image sensor of claim 1, whereinanother interlayer dielectric film is interposed between the colorfilter layer arid the first niicrolens.
 10. The image sensor of claim 1,further comprising a second inicrolens formed on the color filter layerwith a dielectric film interposed therebetween.
 11. The image sensor ofclaim 1, further comprising: a dielectric film formed on the interlayerdielectric film over the color filter layer; a polysilicon patternhaving a cylindrical shape formed on a part of the dielectric film overthe second portion of the photodiode; and a round-type second microlensformed on the dielectric film over the polysilicon pattern.
 12. Theimage sensor of claim 11, wherein the second microlens includes a shellportion and an interior portion, wherein the interior portion is filledwith a lens material or is empty.
 13. The image sensor of claim 11,wherein the second microlens includes: a round-type shell portionenclosing the polysilicon pattern, the round-type shell portion havingan edge separated from the dielectric film; and a filler materialfilling the interior of the shell portion.
 14. The image sensor of claim13, wherein the shell portion is formed of silicon oxide or zirconiumoxide.
 15. The image sensor of claim 13, wherein the filler material isformed of silicon oxide or photoresist.
 16. The image sensor of claim11, wherein the second microlens includes: a round-type first shellportion enclosing the polysilicon pattern, the round-type first shellportion having an edge separated from the dielectric film; and a secondshell portion formed on the first shell portion and the dielectric film.17. The image sensor of claim 16, wherein the first shell portion isformed of silicon oxide or zirconium oxide.
 18. The image sensor ofclaim 16, wherein the second shell portion is formed of silicon oxide orzirconium oxide.
 19. A microlens, comprising: a polysilicon patternhaving a cylindrical shape, wherein the polysilicon pattern is formed ona semiconductor substrate; a round-type shell portion for the microlens,wherein the round-type shell portion encloses the polysilicon pattern;and a filler material filling an interior of the shell portion.
 20. Themicrolens of claim 19, wherein the shell portion is formed of siliconoxide or zirconium oxide.
 21. The microlens of claim 19, wherein thefiller material is formed of silicon oxide or photoresist.
 22. Themicrolens of claim 19, wherein the shell portion has an edge separatedfrom the substrate.
 23. The microlens of claim 19, further comprising aninterlayer dielectric film interposed between the polysilicon patternand the substrate.
 24. The microlens of claim 19, further comprising aninterlayer dielectric film formed on the substrate around thepolysilicon pattern, wherein the interlayer dielectric film has a heightsmaller than a height of the polysilicon pattern.